1. Field of the Invention
The present invention relates to sorbent sheet products which provide rapid sorption and high liquid retention. Such products are useful in disposable incontinent devices, diapers, surgical swabs, bed pads, sanitary napkins, and wipers.
2. Description of the Prior Art
Sorbent sheet products having high fluid sorbency per unit weight and high fluid retention are desirable for sorption of fluids such as body exudates. It has been suggested that the sorbency of fibrous web product may be enhanced by the addition of various additives. U.S. Pat. No. 3,670,731 discloses the addition of hydrocolloidal particles to a fibrous mass, such as wood pulp, by cascading the particles into the fibrous mass. However, mechanical action causes the particles to dust out.
U.S. Pat. No. 4,235,237 discloses hydrocolloidal particles adhered to a fibrous web. This is achieved by contacting a fibrous web with hydrocolloidal sorbent particles dispersed in a volatile liquid, then vaporizing the liquid. Disadvantages of this approach include the need for multiple processing steps, limitations on the amount of particles that can be added to the web, brittleness of the dried web, and the tendency for particles to concentrate at the web surface.
U.S. Pat. No. 4,429,001 discloses the use of high sorbency particles in melt blown fiber webs. The melt blown fibers hold the particles to a large extent, but some dusting out of the particles may occur with mechanical action on the web. European Patent Application No. 0,080,382 also discloses sorbent particles in melt blown fiber webs. U.S. Pat. No. 4,426,417 discloses a nonwoven fiber matrix which includes melt blown fibers and a staple fiber mixture of synthetic and cotton fibers. However, this product sorbs only a limited amount of fluid and retention of fluid when the web is under pressure is low. British Patent Application No. 2,006,614 A discloses a melt blown fiber web treated with a wetting agent. This product also has disadvantages in that only a limited amount of fluid is absorbed and retention of fluid when the web is under pressure is limited.